Sandoyartunnilin is an undersea road tunnel in the Faroe Islands. It connects the main island of Streymoy with Sandoy to the south. The length of the tunnel is 10.8 kilometres (6.7 mi) and the estimated cost is 860 million DKK. The tunnel opened for traffic on 21 December 2023, after which the ferry Teistin ceased its route between Gamlarætt on Streymoy and Skopun on Sandoy. The tunnel crosses the Skopunarfjørður and runs from Gamlarætt to Traðardalur in central Sandoy, near the Inni í Dal stadium.

Streymoy is the largest and most populated island of the Faroe Islands. The capital, Tórshavn, is located on its southeast coast. The name means "island of currents". It also refers to the largest region of the country that also includes the islands of Hestur, Koltur and Nólsoy.